The present invention relates to an internal combustion engine fuel injector comprising a hollow body housing a fuel metering valve; and a support connected to said hollow body and housing an electromagnet controlling an armature of said valve.
In known technology, the armature has a stem guided axially by a fixed guide to a high degree of precision, e.g. with a radial clearance of about 10 microns. Since the stem increases the mass of the movable armature assembly, to reduce the response time of the electromagnet, it has been proposed to disconnect the armature axially from the stem. In known injectors, to connect the stem to the armature, the armature has an integral guide sleeve, and the stem has a groove engaged by a C-shaped retaining member which is housed in a depression on the armature opposite the sleeve.
Known injectors have various drawbacks. First of all, machining the guide sleeve, stem and fixed guide and assembling the injector are complicated, expensive jobs. And secondly, the armature and sleeve must be made of wear-resistant ferromagnetic material capable of withstanding both high-precision machining and wear with respect to the stem.
It is an object of the present invention to provide a fuel injector which is highly reliable, is cheap and easy to produce and assemble, and provides for eliminating the drawbacks typically associated with known injectors.
According to the present invention, there is provided an internal combustion engine fuel injector comprising a hollow body housing a fuel metering valve; and a support connected to said hollow body and housing an electromagnet controlling an armature in turn controlling said valve; said valve closing a control chamber on which high-pressure fuel acts; said valve normally being closed by a closing spring acting on said armature and which overcomes the action of the fuel in said control chamber; and said valve being opened when said electromagnet activates said armature to overcome the action of said closing spring; characterized in that said armature is fitted inside said hollow body by means of a leaf spring hinge comprising a first portion fixed between said hollow body and said support, and a second portion fixed to said armature.